accumulator instead of its sub-registers, $hi and $lo.
We need this change to prevent a mflo following a mtlo from reading an
unpredictable/undefined value, as shown in the following example:
mult $6, $7 // result of $6 * $7 is written to $lo and $hi.
mflo $2 // read lower 32-bit result from $lo.
mtlo $4 // write to $lo. the content of $hi becomes unpredictable.
mfhi $3 // read higher 32-bit from $hi, which has an unpredictable value.
I don't have a test case for this change that reliably reproduces the problem.
llvm-svn: 192119
precision loads and stores as well as reg+imm double precision loads and stores.
Previously, expansion of loads and stores was done after register allocation,
but now it takes place during legalization. As a result, users will see double
precision stores and loads being emitted to spill and restore 64-bit FP registers.
llvm-svn: 190235
invalid instruction sequence.
Rather than emitting an int-to-FP move instruction and an int-to-FP conversion
instruction during instruction selection, we emit a pseudo instruction which gets
expanded post-RA. Without this change, register allocation can possibly insert a
floating point register move instruction between the two instructions, which is not
valid according to the ISA manual.
mtc1 $f4, $4 # int-to-fp move instruction.
mov.s $f2, $f4 # move contents of $f4 to $f2.
cvt.s.w $f0, $f2 # int-to-fp conversion.
llvm-svn: 182042
This option is used when the user wants to avoid emitting double precision FP
loads and stores. Double precision FP loads and stores are expanded to single
precision instructions after register allocation.
llvm-svn: 181718
the temporary register that was used to load the immediate. Currently, it always
returns register $at, but this will change if, in the future, we decide to use
another register.
No changes in functionality.
llvm-svn: 162417
instructions that decrement and increment the stack pointer before and after a
call when the function does not have a reserved call frame.
llvm-svn: 161093
Craig Topper